1. Field of the Invention
The present invention is directed to real time ultrasound imaging of an object, like a biological structure, in multiple scan planes. Designs of efficient ultrasound phased array bulk wave transducers for two-dimensional ultrasound imaging, with several, electronically selectable 2D scan planes, are given. The electronic selection of the 2D scan plane direction allows so rapid switching of the direction that practically real time observation of moving objects like the heart, can be obtained simultaneously in several scan planes. The invention also addresses real time ultrasound monitoring of the cardiac function.
2. Description of the Related Art
In medical ultrasound imaging, one often examines an object through a variety of two-dimensional (2D) scan plane directions to observe the form, regional variations, and volume of the object. In particular one uses such multiple scan plane imaging of the heart to assess regional variations in the wall motion and myocardial contraction/relaxation, as well as to calculate the time varying volume of the heart, or the temporal variation of the fiber stress and strain in the heart. Other situations are observations of fetuses, tumors, etc., especially for calculating the volume to study growth.
In practical clinical examinations, such multiple 2D scan planes are generally obtained through manual movement of the 2D ultrasound probe, where for example with transesophageal measurements of the heart with a 2D phased array probe, special mechanisms have been designed for rotation of the ultrasound array through remote control. A phased array transducer for electronic selection of the ultrasound scan planes in two angular directions has been presented in [1], but this solution has found limited practical use, mainly because one wants to observe the object in more than two planes, generally at least three or four angular directions of the 2D scan plane.
The present invention presents a solution to this problem, with the design of a phased array transducer that allows free electronic selection of the 2D scan plane in more than 2 angular directions, for example 3 or 4 angular directions.